Many telephones, particularly those normally referred to as desktop telephones, have a handset and a base unit, with the handset merely providing a convenient housing for a microphone and a speaker while the base unit provides a hookswitch for connecting and disconnecting the telephone from a telephone central office, a dialpad for initiating telephone calls, and all of the electrical components necessary for the user of the telephone to place and receive calls. The handset is typically connected to the base unit by a handset cord having a handset plug for connection to a handset jack provided in the base unit. A second type of telephone, typically for home use, has the dialpad and hookswitch integrated into the handset so that the base unit merely provides a hookswitch actuating cradle for the telephone. In both types of telephones the handsets include cords and could be described as "corded". However, the present invention is limited to telephones of the type described above having no dialpad nor hookswitch in the handset, which are referred to as "corded telephones" below. A typical such corded telephone is illustrated in FIGS. 1 and 2 of the attached drawings.
A "cordless" telephone herein shall mean a telephone comprised of a base station and a portable terminal (handset). The portable terminal provides all of the essential functions of the telephone, where by contrast the handset of a corded telephone does not. For example, calls may be made and terminated from the portable terminal of a cordless telephone without returning to the base station. Further, cordless telephones generally differ in appearance from corded telephones in ways other than the absence of a cord because of the need for the portable terminal to have a full set of controls (e.g., a dialpad and a talk switch) and normally an external antenna.
An alternative to both corded and cordless telephones is what is referred to herein as "uncorded telephone". An uncorded telephone shall mean a telephone having no cord between the base unit and the handset, but which in mode of operation is essentially the same as a corded telephone.
Users of corded telephones, such as that illustrated in FIGS. 1 and 2, are tied to their telephone's base unit by the handset cord. If, during a conversation, a need arises to retrieve information or perform another task at a location beyond the reach of the handset cord, the user must interrupt his or her conversation and put the handset down. Users do have the option of purchasing a cordless telephone in addition to their existing corded telephone, however, this can be undesirable for a number of reasons:
(1) Cordless telephones are typically expensive. PA0 (2) Some telephone companies charge more for additional telephones within the same residence or office. PA0 (3) Cordless telephones tend to not be as rich in features as existing corded telephones. PA0 (4) Users may want to maintain the method of operation and aesthetics of their existing corded telephone.
Therefore, conversion of an existing corded telephone to uncorded operation would seem to be preferable to purchase of a cordless telephone. However, in the prior art known to the inventor in which conversion of a corded telephone to uncorded operation is disclosed, substantial change to the appearance or method of operation of the corded telephone is a consequence of the conversion.
For example, Nash et al., U.S. Pat. No. 5,010,565, discloses an apparatus and method for adding uncorded handset to an existed corded telephone. While Nash et al. discloses a conversion kit that does not appear to require internal modification of the base unit, installation of the cradle 100 or cradles 150/160 shown in FIGS. 1, 2, and 3 of Nash et al. changes the external appearance of the base unit noticeably. Further, the cordless base 126A/126B illustrated in FIG. 1 and 2 of Nash et al. adds another unit to the user's desktop, with the necessary added connecting cords, and would be difficult to use to convert a wall mounted telephone to uncorded operation. Further, Nash et al. discloses recharging of the handset battery by electrical contacts located in a cradle and in the handset. While such contacts are commonly used in cordless phones, the use of such contacts in a corded telephone converted to uncorded operation would change the appearance and reliability of the telephone significantly.
Steinbeck et al., U.S. Pat. No. 4,752,449, discloses a combination corded/cordless telephone that can be operated either as a corded telephone or, by removing a cord between the handset and base unit, may be operated as a cordless, not an uncorded, telephone. However, no conversion kit for converting corded telephones such as that shown in FIGS. 1 and 2 to uncorded operation is disclosed by Steinbeck et al.
Hannon et al., U.S. Pat. No. 4,908,847, discloses an adaptor set for converting a standard telephone into an uncorded telephone by the replacement of the cord between the handset and the base unit with a two piece adaptor, one adaptor for the handset and one adaptor for the base unit, each adaptor containing a radio frequency transmitter/receiver. The adaptors are clearly visible as appendages to the handset and base unit. The adaptor for the handset would necessarily require a battery, but no means is disclosed for recharging the battery without removal of the battery from the handset adaptor. The need to periodically replace or recharge the battery would be inconvenient to the user. Further, the battery would appear to be subject to constant discharge as no means is disclosed for activating the handset transmitter/receiver only when the handset is off-hook.
Gallo, U.S. Pat. No. 5,680,441, discloses an improved version of the adaptor disclosed in Hannon et al. The continuous discharge of the handset battery is allegedly avoided by a motion detection switch which activates the handset transmitter/receiver only for a period of time after the handset is moved (presumably when it is taken off-hook). Use of a replaceable long-life battery in the handset or recharging of the battery using a recharging jack built into the handset is suggested. The user would have to pay attention the level of remaining battery power to avoid a conversation being interrupted or would have to remember to plug in the battery charger when returning the handset to the base unit. The stationary transmitter/receiver is a separate unit connected to the existing telephone base unit, with the disadvantages of the apparatus disclosed in Nash et al. as discussed above, and is provided with a DC power adaptor and external antenna.
Manzarek, U.S. Pat. No. 4,937,852, discloses an is alternative approach, namely, interposing a base unit and portable unit between the telephone line and a corded telephone. The entire corded telephone is connected to the portable unit, which simulates a telephone line connection, but includes a radio receiver/transmitter for communication with the base unit. The base unit, also containing a radio receiver/transmitter, is connected directly to a telephone line. The entire corded telephone can then be moved around within the range of the radio receiver/transmitters, but the handset is still connected by a cord to the corded telephone base. Carrying the entire telephone around would appear to be less convenient than carrying only a handset as in an uncorded telephone.